Generally a brushless motor (DC motor) is downsized, and can provide a prolonged service life because electrical connection of a brush and a commutator to a rotor attached to a rotation shaft can be eliminated. The brushless motor is provided with an inverter circuit board (motor driver circuit board) which includes an output transistor as a switching element configured to supply drive signals of large electrical current to a stator coil provided around the rotor.
Japanese Patent Application Publication No. 2011-062803 discloses a structure for protecting an inverter circuit board against rainwater and dust. The protective structure includes a heat radiation member for releasing heat from the switching element. Further, constituents of electronic circuit such as electronic components, coil connecting portion, control circuit portion connecting portion, a circuit board, and the heat radiation member are integrally covered with an insulating cover member by molding.